Inkjet printing is a type of printing that creates a digital image by propelling droplets of ink onto a medium, such as paper. The core of an inkjet printer includes one or more the print heads (referred to herein as inkjet heads) having a series of nozzles that are used to spray drops of ink. The structure of an inkjet head typically includes a housing, a series of plates, and a piezoelectric actuator. The housing has an opening for the piezoelectric actuator to pass through, and an inlet that connects to an ink supply (e.g., an ink cartridge). The inlet for the ink supply also connects to a groove in the housing that forms an ink supply channel for the inkjet head.
The plates of the inkjet head are attached to the housing and to one another to form a laminated structure. The laminated structure forms a plurality of ink channels that are each capable of dispersing ink. Each ink channel includes a nozzle, a chamber for ink, and a mechanism for ejecting the ink from the chamber and through the nozzle, which is typically a diaphragm. In order to form the ink channels, a common inkjet head includes a diaphragm plate, a restrictor plate, a chamber plate, and an orifice plate. The orifice plate includes a row of small holes that comprise the nozzles for the inkjet head. The chamber plate includes a row of openings that form chambers for the ink. The restrictor plate also includes a row of openings which form restrictors that fluidly connect the chambers to the ink supply and that control the flow of ink into the chambers. The diaphragm plate forms diaphragms over the chambers with a sheet of a semi-flexible material. The diaphragm plate also includes openings that allow ink to be drawn from the ink supply and into the chambers when the diaphragms vibrate.
The piezoelectric actuator includes a plurality of piezoelectric elements that attach to the diaphragm plate. Each piezoelectric element corresponds to one of the chambers formed in the chamber plate. When electrical signals are selectively applied to the piezoelectric elements, the elements expand and contract. This causes the diaphragms to vibrate over the chambers, which changes the volume of the chambers. The change in the volume of the chamber causes ink to be ejected from the chambers through the nozzles on the orifice plate.
One problem with inkjet heads is that the ink can dry in the nozzles or chambers when the head or individual nozzles are not in use. One or more of the ink channels can therefore become clogged within the head.